Semiconductor image sensors are operated to sense light. Typically, the semiconductor image sensors include complementary metal-oxide-semiconductor (CMOS) image sensors (CIS) or charge-coupled device (CCD) sensors, which are widely used in various applications such as digital still camera (DSC), mobile phone camera, digital video (DV) and digital video recorder (DVR) applications. These semiconductor image sensors utilize an array of image sensor elements, each image sensor element including a photodiode and other elements, to absorb light and convert the sensed light into digital data or electrical signals.
In general, a CMOS image sensor adopts a stacked structure including a micro-lens layer, a color filter layer, a passivation layer and/or a semiconductor layer. However, the intensity of incident light is significantly decreased when the incident light penetrates through these layers. The decreasing of the intensity of incident light results in quantum efficiency degradation of the CMOS image sensor.